The present invention relates to methods and apparatus for the generation of terahertz (THz) radiation and more particularly to compact apparatus for the generation of such radiation.
The THz region (1 THz=33 cmxe2x88x921 or 4 meV) lies in the far infrared spectral range where conventional thermal sources are very weak. For example, a blackbody source at 2,000xc2x0 K. provides less than 1 xcexcW per cmxe2x88x921 of spectral power density for a typical spectroscopy application. Such radiation offers great promise for use in many Important fields, for example diagnostic applications such as the observation of melanoma as well as security systems that rely on imaging of persons or packages that do not submit well to other forms of imaging such as X-ray imaging.
While THz radiation is well known and has been produced in many environments, the generation of such radiation normally requires large pieces of equipment such as particle accelerators or free electron lasers to obtain the energies required to produce such radiation. For example, a free electron laser capable of producing the required high energy input beam (50 MeV) for such a device may be up to 60 feet long. The need for such large devices has limited significantly the use of THz radiation in applications other than those with ready access to such large pieces of equipment. Thus, it would be highly desirable to provide a method and device for the production of intense THz radiation that is of compact size and therefore more readily utilized In areas remote from the large devices usually associated with the production of THz radiation.
It is therefore an object of the present invention to provide a compact device capable of producing intense THz radiation.
According to the present invention, there is provided a compact source of intense THz radiation comprising a short bunch, low energy particle beam source, an accelerator cavity and an electromagnetic wiggler. Application of state-of-the-art superconducting accelerating structures and beam recirculation allows such a THz radiation source to have a small footprint and high average intensity without the need of the larger equipment necessary to produce the large charge per bunch generally associated with the production of THz radiation. Consequently, low emittance electron beams can be used to produce emitted THz radiation of yield high average brilliance.